This disclosure relates generally to semiconductor devices, and more specifically to semiconductor memory devices. In particular, the disclosure relates to volatile memory, such as dynamic random access memory (DRAM). Information may be stored in memory cells of the DRAM as a changed physical property of the memory cell. For example the memory cell may be a capacitive element, and the information may be stored as the charge of the capacitive element. The DRAM may include volatile memory cells, which are memory cells where the physical property may change over time (e.g., the charge on a capacitor may decay over time) which may, in turn, degrade the data stored in the memory cell over time. Thus, it may be necessary to periodically refresh the memory cells to maintain information fidelity in the memory (e.g., by restoring the memory cell to an initial charge level).
As memory components have decreased in size, the density of memory cells has greatly increased. Repeated access to a particular memory cell, or group of memory cells (often referred to as a ‘row hammer’) may cause an increased rate of data degradation in nearby memory cells. It may be desirable to identify and refresh memory cells affected by the row hammer. These targeted refreshes may need to be interspersed amongst the regular periodic refreshes which are carried out on rows which are not experiencing a row hammer effect.